1. Field of the Invention
This invention relates generally to an improvement in the field of flow regulation devices and more particularly, but not by way of limitation to an automatic fluid flow regulator particularly adapted to split the flow of a fluid into two separate branches and to maintain the ratio of such flows in a predetermined ratio.
2. Brief Description of the Prior Art
In fluid distribution systems it is often necessary to split the flow of a fluid into two branches, with the ratio of the flow of fluid into the two branches being maintained in a predetermined ratio. In many instances this ratio may be kept constant by automatic regulating valves. However, in some applications, the use of such automatic valves with their associated sensors, springs, coils and the like are not practical, for example, in cryogenic fluid systems. The present invention will automatically adjust the flow of fluid in each branch of a fluid distribution system to maintain a constant predetermined ratio and at the same time avoid the use of sensors, springs or valves. It is especially difficult in cryogenic systems having two loops to confirm that both loops of the system are receiving sufficient coolant during cooldown. The automatic flow regulator of the present invention is intended to automatically ensure that both loops do indeed receive the proper amount of coolant.
The presently available fluid control means while perhaps successful in solving other problems do not appear to be capable of application to maintaining fluid flows in a predetermined ratio in a cryogenic system without recourse to various unacceptable mechanical elements such as valves, springs, or sensors. One example is the flow divider valve of U.S. Pat. No. 4,204,554 issued on May 27, 1980 to Alistair G. Taig. The Taig patent discloses a flow divider valve cooperating with a housing to control flow between an input port, a first output port, and a second output port. The valve comprises a double seat valve member centrally mounted within a valve body by means of an integral resilient diaphragm that enables the valve to preferentially direct fluid flow towards the output port presenting the higher back pressure. This arrangement is in contradistinction to the present invention which maintains equilibrium in two branches of a cryogenic system.
U.S. Pat. No. 3,924,650 issued to Donald J. Parquet on Dec. 9, 1975 for Fluid Flow Divider Valve discloses a valve having a hollow spool shiftable in a valve body to regulate fluid flow through two outlet openings. Compression springs are disposed at opposite ends of the spool for centering the spool relative to the valve body while a fluid by-pass passageway is provided in the spool for permitting fluid to pass to an outlet opening when the spool is shifted to an extreme position which would otherwise close off the outlet opening and thereby preclude an undesirable increase in upstream pressure when the spool has been shifted to diminish flow in one branch. The use of springs of the Parquet device would render it non-functional for use in a cryogenic environment.
U.S. Pat. No. 3,370,602 issued on Feb. 27, 1968 to Vaughn A. Nelson for an Automatic Flow Diverter Valve discloses a reciprocalably operable valve interposable between a source of fluid pressure and two hydraulic circuits wherein pressure demands in one of the circuits is effective to cause automatic shifting of the spool for directing a substantial portion of the fluid flow from the pressure source to the circuit creating the demand for said flow. This valve acts to divert even more fluid flow from one affected branch to the other. This action of this valve will reinforce the initial disturbance rather than counteract it. On the other hand, the automatic fluid flow regulator of the present invention will automatically adjust the flows in both branches to restore the previous ratio of volumetric flows in the two branches.
In Japanese Pub. No. 12/90/70, Class 66 A8Z, dated Oct. 30, 1965 by Shinmeiwa Kogyokik, there is disclosed a pressure compensation type proportional valve capable of varying flow rate at an optional rate. Means in the form of metering needle valves are provided to vary the flow from the input port to the two output orifices but this device provides no means to automatically equalize the pressures in two branches should there be a disturbance downstream in one of the branches since this device acts only on pressure changes at the input port of this device.
The inadequacies of previous flow regulation devices as applied to the maintenance of equilibrium in two branches of a cryogenic system has been illustrated and the automatic fluid flow regulator of the present invention is believed to have resolved these inadequacies for such an application.